The good chemist is tasket with determining the concentration ofmanganese for a water sample drawn from a well next to a mine. Toanalyze the sample using absorbance spectroscopy, she prepares sixsample (0-5) by adding 10.00 mL well water to 50.00-mL volumetricflasks, then adding increasing volumes of 25.00 ppm maganesesolution, and diluting the resulting solution to 50.00 mL with 0.1M HNO3. Final analysis at lambda(max)= 280 nm produced a graph ofabsorbance vs ppm Mn with best-fit line y = 0.0428x + 0.0487.
a) What is the concentration in ppm of manganese in the wellwater sample?
b) A field method of analysis was developed for testing soilnear the mine where a .570 g sample of soil is quickly dissolved inacid with an oxidizing agent and diluted to 100 mL.
i) While you wait for the extraction, you calivrate yourUSB-spectrometer with a 3.15x10^-4 M standard of MnO4- with anaverage absorbance of .407 at 565 nm in a 1 cm cuvette. A blanksolution made from DI water and acid had an absorbance of .078.Find the molar absorptivity of permanganate complex
ii) A few mL of the unknown solution is placed in a 1 cm celland the transmission is found to be 30% at 565 nm. Calculate theconcentration of manganese in the extracted sample.
iii)What was the weight percent of manganese in the originalsoil sample. iv) Explain in one sentence why permanganate appearsto be a purple color
